In this post I will show you how to create dependent lookups. Dependent lookups are great feature to emulate something similar to dependent drop downs in .Net . The entity structure as shown in the following diagram is used to demonstrate this implementation.
Now as per the above entity structure create the following form structure in CRM.
Now to ensure that you get only those categories in the category lookup based on the brand selected in the product brand lookup , double click on the Product Category Field in Form Editor Screen, which will open the following screen.
The Related Records Filtering section in the above diagram is the key to your success. In this section make sure you tick the checkbox “Only show records where:” which will give options to select value from drop down based on which you will filter value in the category lookup field. The Checkbox “Allow users to turn off filter” restricts user to enter only categories which have the brand selected in the brand lookup.
Hope this helps you. In case u have still some issues you can always post your comments.